DM soliton pulses have the property of propagating periodically without deformation in a non-linear medium, since these particular pulses constitute a solution to the non-linear Schrödinger equation. Nevertheless, accumulated amplified spontaneous emission noise, in particular as generated by optical amplifiers disposed at regular intervals along the optical fiber, disturbs the propagation of such pulses by generating intensity fluctuations and so-called Gordon-Haus time jitter. Collisions between DM soliton pulses belonging to different channels of the optical fiber also constitute a source of jitter (known as collision jitter).
While pulses are propagating along an optical fiber, their time and spectral profile and also their time and spectral positions are modified under the effects of various disturbing influences, whence the need to perform optical regeneration.
An optical pulse-regenerator device is already known in the state of the art that comprises an optical bandpass filter adapted for time-synchronizing and intensity-stabilizing pulses, in particular the device disclosed in the document entitled “Linear stability analysis of dispersion-managed solitons controlled by filters” by J. Kumasako and M. Matsumoto, taken from the Journal of Lightwave Technology, Vol. 18, No. 8, August 2000.
The filter is adjusted by acting on its center frequency and on its bandwidth. The use of a bandpass filter makes it possible firstly to synchronize pulses in time by re-centering them on the center frequency of the filter, and secondly to stabilize the intensity of the pulses by filtering the extreme frequencies of the spectrum of the pulses, which extreme frequencies have appeared during pulse propagation.
For the filter to be effective, it must be narrow enough to limit the spectrum width of a pulse and to eliminate noise. Nevertheless, if the filter is too narrow, it runs the risk of changing the optimum waveform of the pulse with the danger of destabilizing and disturbing its propagation in the optical fiber. Selecting the spectrum width of the filter is thus the result of a compromise.
Because the filter used must not be too narrow, the filter is ineffective in eliminating amplified spontaneous emission noise. Consequently, the prior art regenerator device is ineffective in eliminating such noise, which therefore tends to accumulate as pulses are transmitted along the optical fiber. This is particularly true of a wavelength-multiplexed line.